I have the exact same problem and it has gotten worse and worse over time. It was worst in my last year of school and now it is somewhat better as I am in a gap/rest between different stages of my life. I have gone to doctors multiple times and gotten multiple blood tests and it has all come back fine. I was told by my therapist that it could be caused by my feelings and my lifestyle, as it seems to be depression-related (it correlates positively with how depressed I am). I can't give you any good advice because I don't know what to do either, sorry.

It is really embarrassing because everyone thinks I am kinda antisocial and very lazy. They think I am some kind of snob for not wanting to do a lot of things but in reality it's because I feel so tired and blank.

Cliché as it may be, know that you are not alone, I think that most depressed people get these kinds of symptoms.

On the bright side, if what we have is the same thing, as your other depression symptoms are alleviated you should feel much less tired.